MTU - PING

ADSL set MTU 1480

ethernet 1500byte
MSS = 1500-20(ip)-20(tcp) = 1460

therefore,  1452 + 20 (IP) + 8byte (ICMP) = 1480

C:\Users\jonny>ping 8.8.8.8 -f -l 1452

Pinging 8.8.8.8 with 1452 bytes of data:
Reply from 8.8.8.8: bytes=1452 time=48ms TTL=56
Reply from 8.8.8.8: bytes=1452 time=48ms TTL=56

http://smallvoid.com/article/tcpip-mtu-size.html
http://www.zytrax.com/tech/protocols/tcp.html
http://www.cisco.com/en/US/tech/tk175/tk15/technologies_tech_note09186a0080093bc7.shtml